Condenser Performance Improvement is an increasingly important issue for both nuclear and fossil fueled generating systems. Condenser performance deficiencies can easily increase heat rate by 100 BTU's per Kw-hr and often by as much as 400 BTU's per Kw-hr. Condenser performance deficiencies can also limit plant load during summer operation.

HES offers the utility industry a three-dimensional condenser modeling program (CONDEV), a Mott MacDonald development.

Utilizing computational fluid dynamics (CFD) analysis techniques, steam surface condenser geometry can be accurately modeled in a three-dimensional grid, and the effects of pressure drop and both heat and mass transfer analyzed in order to predict steam velocity, pressure, air concentration and cooling water temperature at any location within the condenser shell.

Prior to constructing the model, it is first necessary to assemble information detailing condenser internals fabrication. Baffles, rain trays, support members and piping must be accurately positioned and dimensioned.

In most cases, it is essential to perform a condenser internals visual inspection in order to "as-built" the unit.

Once condenser geometry has been accurately modeled, boundary conditions are defined based upon expected operating conditions. The boundary conditions include steam flow rates, circulating water inlet temperature, circulating water flow rate and pressure at the air extraction vent.

Results are presented in the form of color keyed plots, illustrating the magnitude and direction of steam flows and pressure gradients within the shell. The model can be sectioned at any desired longitudinal or vertical location for the plots. Summary data is presented in tabular form.

Validation of model results is accomplished through comparison of predicted condenser shellside pressures of and circulating water temperature with measured values.

Prior to attempting model validations, an instrumentation review must be performed in order to ensure that all measured values are sensed in the proper locations with instrumentation of sufficient accuracy.

Once model validation has been achieved, runs are performed simulating modifications to condenser internals geometry in order to assess the resultant impact upon condenser pressure.

Typically simulated modifications include creation of steam lanes by tube removal and removal or relocation of baffles. More involved modifications may include repositioning air removal sections or removing tubes to achieve better steam distribution to the bottom of the bundle.

The impact of each modification on condenser pressure can then be evaluated against modification costs to determine the optimal course of action.

CONDEV offers the utility industry an accurate and cost effective method of evaluating the most efficient means of affecting condenser performance improvement.